Hybrid Electric Vehicles: Overview ppt

Hybrid Electric Vehicles: Overview H Kabza, University of Ulm, Ulm, Germany & 2009 Elsevier B.V. All rights reserved. Introduction R oad traffic is one of the major consumers of energy, par- ticularly in w estern industrialized countries, and globally it exhibits the highest growth rate in energy consumption of all sectors. In the Organisation for Economic Coo peration and D e v elopment (OECD) countries, more than 33% of the total final energy consumption goes into the transpor- tation sector, amounting to more than 11% of the w orld’s total p rimary energy consumed. Virtually all of these vehicles are operated with in- ternal combustion engines (ICEs) fueled with gasoline, diesel, or – to a very lower extent – different kinds of gases (compressed natural gas (CNG), liquefied pet- roleum gas, liquefied natura l gas) or biomass-based fuels (bio-diesel, ethanol, or vegetabl e oil). The combination of two factors made this enormous quantitative development possible within a century: on the one hand, the robustness and easy scalability of the ther- modynamic conversion process from heat to mechanical energy in the ICE; on the other, the extremely favorable properties of liquid hydrocarbons as energy carriers, that is, their unparalleled energy density in terms of weight and volume, easiness to handle, and the seemingly abundant availability from oil wells. Only the problems associated with the enormous input and output quantities and their implications on a global scale bring the de- ficiencies of the ICE more clearly into view today: it ex- hibits an only very small operational regime with optimum efficiency, and this optimum efficiency is rather poor, approximately between 35% and 45% (cf. Figure 1). Moreover, in practical applications, this optimum effi- ciency regime is used only occasionally, if at all, and there are undesirable emissions associated with the combustion process. In addition, as ICEs do not provide any torque at zero speed, they need an electric motor (EM) for starting, and there are more or fewer idling phases depending on the driving situation. In contrast, an EM is ideal for traction applications. It does not consume energy at standstill and provides maximum torque at zero speed. It can be operated re- versely not only in the direction of rotation but also by acting as a generator, that is, converting mechanical en- ergy on the shaft into electrical energy, thus enabling regenerative braking in this way. Furthermore, EMs allow short-term overloads, the extent and duration of which depend on the construction of the machine and cooling. 240.0 220.0 200.0 180.0 160.0 140.0 120.0 100.0 80.0 60.0 40.0 20.0 0.0 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 Speed (rpm) Torque (N m) 40 20 38 40% 34 36 10 34 32 30 28 26 24 22 20 20 20 22 24 20 30 28 40 50 30 32 34 38 50 70 80 60 36 Figure 1 Typical efficiency map of an internal combustion engine (turbo direct injection diesel) with contour lines of constant efficiency and hyperbolas of constant power in kW. Source: EPA; http://www.researchcaucus.org/docs/Charles_Gray_Talk.ppt as of 20 March 2007. 249 . Hybrid Electric Vehicles: Overview H Kabza, University of Ulm, Ulm, Germany & 2009 Elsevier B.V. All rights. combustion process. In addition, as ICEs do not provide any torque at zero speed, they need an electric motor (EM) for starting, and there are more or fewer idling phases depending on the driving. rotation but also by acting as a generator, that is, converting mechanical en- ergy on the shaft into electrical energy, thus enabling regenerative braking in this way. Furthermore, EMs allow short-term